Yarrow (Achillea millefolium) has a long history as an herbal remedy applied to the skin for wounds, cuts, and abrasions. The genus name Achillea is derived from the mythical Greek character, Achilles, who reportedly carried it with his army to treat battle wounds. Dried yarrow stalks are used as a randomizing agent in I Ching divination.

Currently, there are no high-quality trials available investigating yarrow. Although a laboratory study demonstrated yarrow's antibacterial effects, one poor-quality study using an herbal combination of yarrow, juniper, and nettle did not find any benefit on plaque or gingivitis inhibition.

These uses have been tested in humans or animals. Safety and effectiveness have not always been proven. Some of these conditions are potentially serious, and should be evaluated by a qualified healthcare provider.

GRADE *

Based on laboratory study, yarrow grass water extract showed antibacterial effects on Staphylococcusaureus. However, human study using a combination formula (including yarrow, juniper, and nettle) found no effect on gingivitis or plaque inhibition. Additional human study is needed in this area.

C

* Key to grades

A: Strong scientific evidence for this useB: Good scientific evidence for this useC: Unclear scientific evidence for this useD: Fair scientific evidence for this use (it may not work)F: Strong scientific evidence against this use (it likley does not work)

Tradition / Theory
The below uses are based on tradition, scientific theories, or limited research. They often have not been thoroughly tested in humans, and safety and effectiveness have not always been proven. Some of these conditions are potentially serious, and should be evaluated by a qualified healthcare provider. There may be other proposed uses that are not listed below.

There is no proven effective dose for yarrow in adults. A rinse with 10 milliliters of mouthwash twice a day for a period of three months as been studied in human volunteers; however, the rinse did not show any beneficial effects on plaque growth and gingival health.

Children (younger than 18 years)

There is no proven effective dose for yarrow in children.

Safety
The U.S. Food and Drug Administration does not strictly regulate herbs and supplements. There is no guarantee of strength, purity or safety of products, and effects may vary. You should always read product labels. If you have a medical condition, or are taking other drugs, herbs, or supplements, you should speak with a qualified healthcare provider before starting a new therapy. Consult a healthcare provider immediately if you experience side effects.

Allergies

Avoid in individuals with a known allergy or hypersensitivity to yarrow (Achillea millefolium), its constituents, or members of the Compositae/Asteraceae family. Cases of allergic contact dermatitis have been described since 1899. There have been reports of occupational asthma and atopic dermatitis from dried yarrow flowers. Yarrow contains sesquiterpene lactones and is often used in patch testing for allergies. Potential side effects of allergy may include skin irritation or light sensitivity.

Cross-reactions between chrysanthemum and yarrow have been reported, and sesquiterpene lactones are thought to be the cause of the cross-reaction and sensitization.

Side Effects and Warnings

There is limited high-quality evidence available describing the adverse effects of yarrow. Yarrow may cause atopic dermatitis or urticaria ("hives") due to its sesquiterpene lactone content. Yarrow may also cause skin irritation or light sensitivity. Use cautiously in patients with photosensitivity.

Use cautiously in patients who are pregnant or planning to become pregnant, based on animal study showing reduced fetal weight and increased placental weight. Yarrow has traditionally been used as an Abortifacient (induces abortion), emmenagogue (induces menstruation), contraceptive, and for stimulating uterine contractions.

Pregnancy and Breastfeeding

Yarrow is not recommended in pregnant or breastfeeding women as it has traditionally been used as an abortifacient (induces abortion), emmenagogue (induces menstruation), contraceptive, and for stimulating uterine contractions.

Based on its coumarin content, yarrow may increase the risk of bleeding when taken with drugs that increase the risk of bleeding. Some examples include aspirin, anticoagulants ("blood thinners") such as warfarin (Coumadin®) or heparin, anti-platelet drugs such as clopidogrel (Plavix®), and non-steroidal anti-inflammatory drugs (NSAIDS) such as ibuprofen (Motrin®, Advil®) or naproxen (Naprosyn®, Aleve®).

Yarrow may interfere with blood pressure medications.

Potential side effects of yarrow allergy may include phytodermatitis, including irritant plant dermatitis, phototoxic and photo-allergic dermatitis, allergic dermatitis, and airborne contact dermatitis. Caution is advised when taking other photosensitizing agents, as side effects may increase.

Interactions with Herbs and Dietary Supplements

Based on its coumarin content, yarrow may increase the risk of bleeding when taken with herbs and supplement that are believed to increase the risk of bleeding. Multiple cases of bleeding have been reported with the use of Ginkgo biloba, and fewer cases with garlic and saw palmetto. Numerous other agents may theoretically increase the risk of bleeding, although this has not been proven in most cases.

Yarrow may interfere with blood pressure agents.

Potential side effects of yarrow allergy may include phytodermatitis, including irritant plant dermatitis, phototoxic and photo-allergic dermatitis, allergic dermatitis, and airborne contact dermatitis. Caution is advised when taking other photosensitizing agents, such as St. John's wort, as side effects may increase.

The information in this monograph is intended for informational purposes only, and is meant to help users better understand health concerns. Information is based on review of scientific research data, historical practice patterns, and clinical experience. This information should not be interpreted as specific medical advice. Users should consult with a qualified healthcare provider for specific questions regarding therapies, diagnosis and/or health conditions, prior to making therapeutic decisions.